The strongly adherent, flaw-free coatings obtained by electrophoretic depositions (EPD) of certain types of polymers have been found to be useful as primers on graphite or carbon reinforcing materials to provide uniform, thin films that yield excellent adhesion and corrosion protection. This type of film has also been investigated as a primer coating for an adhesive joint between metals. An attempt was also made to obtain improved mechanical properties for graphite fiber-epoxy composites when selected electrophorettable resins were electrodeposited onto the surface of the fibers to form an interphase layer between the fiber and the resin matrix. (See R. V. Subramanian et al., "Electrodeposition of Polymers on Graphite Fibers on Composite Properties," Proc. 33rd Ann. Conf. Reinforced Plastics/Compos. Int., Soc. Plast. Ind. 1978, Section 20-F, pp. 1 to 8.). The basic chemistry system used was a maleic anhydride copolymer deposited anodically from an aqueous system onto the graphite fibers in a continuous coating line. Composites were made using primed fiber-epoxy prepregs which were tested in a variety of ways. However the test data indicated that the physical properties of the composites made from graphite fibers onto which the polymers were electrodeposited were not improved as a result of this fiber treatment. In particular, laminate failures occurred because of a lack of adhesion between the impregnating resin and the fibers, or because a chemical graft failed to form between the electrophoretable resin and the fiber, or because a chemical bond between the interphase resin and the matrix resin failed to form. As a result, the interlaminar shear strength of the composite was decreased.